Sounds like you already know what you need to know about it? It's a single shot bolt action 22 rimfire that will take shorts, longs, and long rifle ammo (s-l-lr).

The Revelation 100a was contracted by Western Auto Stores between the 1940's and 50's (earliest I've heard was 1938). It was produced by Mossberg, identical to their Model 321. Just a bare bones rifle, but should be a fine plinker. Nothing fancy, but a workhorse nonetheless.